From aeaf9addc0cbdc101bd0a55b558467338507b232 Mon Sep 17 00:00:00 2001
From: Bhargava Shastry <bhargava.shastry@ethereum.org>
Date: Tue, 8 Feb 2022 12:18:47 +0100
Subject: [PATCH] Refactor FuzzerSolverInterface.

Co-authored-by: chriseth <chris@ethereum.org>
---
 .../lpsolver/FuzzerSolverInterface.cpp        | 76 +++----------------
 .../ossfuzz/lpsolver/FuzzerSolverInterface.h  | 30 --------
 2 files changed, 9 insertions(+), 97 deletions(-)

diff --git a/test/tools/ossfuzz/lpsolver/FuzzerSolverInterface.cpp b/test/tools/ossfuzz/lpsolver/FuzzerSolverInterface.cpp
index fc7cb3ffa..ee5534e13 100644
--- a/test/tools/ossfuzz/lpsolver/FuzzerSolverInterface.cpp
+++ b/test/tools/ossfuzz/lpsolver/FuzzerSolverInterface.cpp
@@ -15,6 +15,8 @@
 
 #include <test/tools/ossfuzz/lpsolver/FuzzerSolverInterface.h>
 
+#include <range/v3/view/enumerate.hpp>
+
 using namespace solidity::test::fuzzer::lpsolver;
 using namespace solidity::util;
 using namespace std;
@@ -25,69 +27,22 @@ FuzzerSolverInterface::FuzzerSolverInterface(bool _supportModels):
 	m_solvingState.variableNames.emplace_back("");
 }
 
-LinearExpression FuzzerSolverInterface::constant(rational _value)
-{
-	return LinearExpression::factorForVariable(0, _value);
-}
-
-LinearExpression FuzzerSolverInterface::variable(
-	rational _factor,
-	string const& _variable
-)
-{
-	return LinearExpression::factorForVariable(variableIndex(_variable), _factor);
-}
-
-void FuzzerSolverInterface::addLEConstraint(LinearExpression _lhs)
-{
-	// Move constant to RHS
-	if (_lhs[0])
-		_lhs[0] = -_lhs[0];
-	m_solvingState.constraints.push_back({move(_lhs), false});
-}
-
-void FuzzerSolverInterface::addEQConstraint(LinearExpression _lhs)
-{
-	// Move constant to RHS
-	if (_lhs[0])
-		_lhs[0] = -_lhs[0];
-	m_solvingState.constraints.push_back({move(_lhs), true});
-}
-
 LinearExpression FuzzerSolverInterface::linearExpression(vector<int> _factors)
 {
-	bool first = true;
-	unsigned count = 0;
 	LinearExpression lexp;
-	for (auto f: _factors)
-	{
-		if (first)
-		{
-			first = false;
-			lexp += constant(f);
-		}
+	lexp.resize(_factors.size());
+	for (auto&& [index, value]: _factors | ranges::views::enumerate)
+		// Move constant term to RHS.
+		if (index == 0)
+			lexp[index] = -rational{value};
 		else
-			lexp += variable(f, "x" + to_string(count++));
-	}
+			lexp[index] = rational{value};
 	return lexp;
 }
 
-void FuzzerSolverInterface::addEQConstraint(vector<int> _factors)
-{
-	addEQConstraint(linearExpression(_factors));
-}
-
-void FuzzerSolverInterface::addLEConstraint(vector<int> _factors)
-{
-	addLEConstraint(linearExpression(_factors));
-}
-
 void FuzzerSolverInterface::addConstraint(pair<bool, vector<int>> _constraint)
 {
-	if (_constraint.first)
-		addEQConstraint(_constraint.second);
-	else
-		addLEConstraint(_constraint.second);
+	m_solvingState.constraints.push_back({linearExpression(move(_constraint.second)), _constraint.first});
 }
 
 void FuzzerSolverInterface::addConstraints(vector<pair<bool, vector<int>>> _constraints)
@@ -121,16 +76,3 @@ string FuzzerSolverInterface::lpResult(LPResult _result)
 		return "infeasible";
 	}
 }
-
-size_t FuzzerSolverInterface::variableIndex(string const& _name)
-{
-	if (m_solvingState.variableNames.empty())
-		m_solvingState.variableNames.emplace_back("");
-	auto index = findOffset(m_solvingState.variableNames, _name);
-	if (!index)
-	{
-		index = m_solvingState.variableNames.size();
-		m_solvingState.variableNames.emplace_back(_name);
-	}
-	return *index;
-}
diff --git a/test/tools/ossfuzz/lpsolver/FuzzerSolverInterface.h b/test/tools/ossfuzz/lpsolver/FuzzerSolverInterface.h
index a93c5a040..114821f7e 100644
--- a/test/tools/ossfuzz/lpsolver/FuzzerSolverInterface.h
+++ b/test/tools/ossfuzz/lpsolver/FuzzerSolverInterface.h
@@ -36,33 +36,6 @@ class FuzzerSolverInterface
 public:
 	FuzzerSolverInterface(bool _supportModels);
 
-	/// @returns constant rational.
-	solidity::util::LinearExpression constant(solidity::util::rational _rationalConstant);
-
-	/// @returns linear expression that equals zero.
-	solidity::util::LinearExpression zero()
-	{
-		return constant(0);
-	}
-
-	/// @returns product of a rational factor and variable.
-	solidity::util::LinearExpression variable(
-		solidity::util::rational _factor,
-		std::string const& _variable
-	);
-
-	/// Adds less-than-equal-zero constraint to solver.
-	void addLEConstraint(solidity::util::LinearExpression _lhs);
-
-	/// Adds equal-to-zero constraint to solver.
-	void addEQConstraint(solidity::util::LinearExpression _lhs);
-
-	/// Adds less-than-equal constraint from vector of factors.
-	void addLEConstraint(std::vector<int> _factors);
-
-	/// Adds equal-to constraint from vector of factors.
-	void addEQConstraint(std::vector<int> _factors);
-
 	/// Adds @param _constraint to LP solver.
 	void addConstraint(std::pair<bool, std::vector<int>> _constraint);
 
@@ -79,9 +52,6 @@ public:
 	std::string checkResult();
 
 private:
-	/// Adds variable if necessary to LP solver state and @returns index of variable.
-	size_t variableIndex(std::string const& _name);
-
 	/// @returns LP result as string.
 	std::string lpResult(solidity::util::LPResult _result);